1. Field of Invention
Embodiments of the present invention relate to a hybrid-powered slow-speed vehicle, a method for extending electric-vehicle travel-range, and a method of hybrid-vehicle manufacture.
2. Background and Prior Art
Sister vehicles in fundamental respects, battery-electric golf cars (legal top speed generally less than 32 km/hr, 20 mph), battery-electric low-speed-vehicles (“LSV's”, legal top speed generally 32 to 40 km/hr, 20 to 25 mph), and other residential and commercial battery-electric slow-speed (BESS) vehicles have won a growing public interest and consumer following for business, social, governmental, utility, and recreational uses. They share fundamental similarities in their primary battery-electric powertrain systems and their performance characteristics, though may differ in wheel and wheelbase dimensions and configurations (see prior art illustrations, FIGS. 1-6 showing various non-exclusively exemplary wheelbase and primary-powertrain configurations). Slow-speed electric vehicles today—advantageous in their smooth, quiet, clean, odorless, and quick-startup qualities—are very common in retirement and other planned communities, and increasingly common in other residential and commercial settings.
Vehicles of this zero-emission sort have arguably helped reduce and at the least have helped shift the collective greenhouse-gas and particulate emissions and vehicle-noise pollution from sites of their uses. Strikingly, however, battery-electric powered vehicles in this slow-speed group offer substantially shorter travel ranges than their counterparts that have primary drivetrains powered by small, generally nonroad-classified, internal combustion engines (ICE). Additionally, as state of battery-charge dwindles in the battery-electrics, many show declining acceleration, declining top-speed, and undesired deceleration on rising grades.
Among the many well-known prior art examples sharing similarly-slow vehicle top-speeds under propulsion of a primary battery-electric powertrain are various models of a front-wheel-drive BESS-vehicle that embodies certain aspects of U.S. Pat. No. 5,890,554 issued to Sturges on Apr. 6, 1999. Reference full-charge travel-range is roughly 48-56 km (30-35 ml) for these vehicles. (See FIG. 7 listing certain vehicle-specifications for one exemplary two-passenger model of this BESS-vehicle and FIGS. 8A-C illustrating three views of an embodiment of this vehicle that will be recognizable to those familiar with the art). Travel ranges for the newer embodiments are substantially unchanged from the older. Other BESS-vehicles having the more common rear-wheel-drive primary powertrain configurations (as non-exclusively exemplified in FIG. 2) constitute numerous additional prior-art examples. Many of the latter have body structures reflecting more traditional golf cart features (see FIG. 9 illustrating one embodiment of a golf-car-style BESS-vehicle). Stretch cargo-carrying and passenger-toting chassis versions (not shown) are also well-known in the art. Some of the vehicles in this group are marketed with claims of full-charge travel ranges as high as 96 km (60 ml); but large numbers of both the newer and older vehicles among these BESS-vehicles are well-known to have generally far-lesser ranges.
Beginning on fully-charged traction batteries, BESS-vehicles having comparable components and similarly undesirably-limited travel ranges, still may vary substantially among and within themselves in the magnitudes of their range-limits. Battery capacity is a primary range-defining specification for each. Range variations in like vehicles can be linked in part to the impacts on those battery capacities from such factors as battery life-cycle status, vehicle-driving styles, road-load demands, and even less controllably, from ambient temperatures. Battery power densities and the dependent vehicle-ranges may precipitously fall by half or more under such influences.
Standard traction batteries need lengthy deep chargings, commonly 8-12 hours, plus more frequent shallower opportunity-rechargings to sustain long life and good service. “Opportunity fast-charging” of traction batteries has proponents; but an infrastructure required to provide conveniently available fast-charges in an electric vehicle community poses significant drawbacks in the expenses and liabilities that accompany set-up and operations. In addition, the minimum fifteen to twenty-minute travel interruptions to users seeking fast-charges (and longer times, if consumer not be first-in-line) constitute further disadvantage. Furthermore, frequent fast-charging can shorten battery life substantially, thereby increasing rates of travel-range decline and overall travel costs in the expense of required replacement batteries coming even sooner.
Solar panel vehicle-roofs have been taught as a supplemental contributor to traction battery recharging. However, even in Sunbelt communities the low amperage solar trickle charging from such small-dimensioned panels provides only modest extensions of daily plug-in travel ranges in these solar-supplemented BESS-vehicles.
Prior art has taught alternative battery types, replacing the standard deep-cycle flooded lead-acid traction batteries in most common use. However, initial battery cost, secondary initial expenses (new charger and controller), future dead-battery replacement costs, limited availability of certain battery types, environmental concerns, and worrisome safety hazards (heat and fire) have been and remain substantial drawbacks.
As expansions of missions cause desired daily travel distances for vehicles of this sort to rise, limitations and uncertainties of travel-range per full battery-charge present an increasing challenge to meeting consumer-needs and providing user-satisfaction from a BESS-vehicle. The rising daily-travel objectives cultivate renewed though conflicted appeal of the generally much longer-ranged and consistently powerful, solely ICE-powered vehicles, even with their fossil-fuel-use related drawbacks.
Hybridization of power sources to gasoline plus battery-electric in advantageous combinations has become increasingly-known in today's highway-classified vehicles. However, ICE-electric hybridization configurations have been taught in only limited forms for BESS-vehicles. Contributing recharge to battery during vehicle operation, portable gasoline-powered inverter-generators accessorizing LSV's has been publicly exhibited as one series-hybrid gas-electric travel-range extension tactic. (See Internet Reference path <evtrader.strongpossibilities.com/forums/viewtopic.php?t=65&start=45>) Drawbacks include the modest range gain, estimated at only about 18 km (11 ml) at a cruising vehicle-speed of 48 km/h (25 mph). Other disadvantages include: a) required manual recoil start of generator; b) continuous engine operation throughout stop-start travels; c) fuel-energy transfer inefficiencies.
No prior art teachings have proposed, included, or envisioned a parallel ICE-electric power-hybridization for its advantages and solutions to certain limitations and disadvantages of today's BESS-vehicles. More specifically, an auxiliary-propelling ICE-powertrain in a slow-speed primary-drive battery-electric vehicle—a powertrain combination useful in economically extending vehicle travel-range, extending battery life, and preserving operator convenience, while still promoting overall-reduced local emissions, optional noise reductions, and other advantages of the battery-electric vehicle over those of solely ICE-powered counterpart vehicles—has not been taught until now.
Various electric golf cars, LSV's, and others in their BESS-vehicle family in many ways are meeting the transportation needs and related greenhouse-gas and noise-pollution concerns of their owners and operators. Still, there is and has been a long-unanswered need for a better solution to the relatively short full-charge travel-ranges and other power-related inadequacies and costs in BESS-vehicles.